title: Prenatal diagnosis of a double bisatellited marker with an unusual copy number ratio.
abstract: Prenatal diagnosis, by amniocentesis, revealed mosaicism with respect to a bisatellited, apparently dicentric, DA/DAPI positive, de novo marker. The following cell lines were observed in decreasing order of frequency: 46,XX greater than 48,XX,+mar,+mar much greater than 47,XX,+mar. The pregnancy was terminated and post-mortem examination revealed an apparently normal fetus. Cytogenetic studies of fetal and placental tissues revealed approximately the same level of mosaicism together with the unusual copy number ratio seen in the amniotic fluid cultures. Non-disjunction at the first post-zygotic mitotic division giving rise to a mosaic: 46,XX/48,XX,+mar,+mar followed by subsequent mitotic instability of the marker could account for the unusual copy number ratio.
authors.affiliation: East Anglian Regional Genetics Service, Addenbrookes Hospital, Cambridge, U.K.
authors.forename: J J
authors.initials: JJ
authors.lastname: Waters
authors.forename: M E
authors.initials: ME
authors.lastname: Ferguson-Smith
authors.forename: N
authors.initials: N
authors.lastname: Carter
authors.forename: J L
authors.initials: JL
authors.lastname: Alexander
authors.forename: S V
authors.initials: SV
authors.lastname: Hodgson
mesh_terms: D000328:Adult; D000649:Amniocentesis; D005260:Female; D005819:Genetic Markers; D006801:Humans; D007621:Karyotyping; D009030:Mosaicism; D011247:Pregnancy
chemical_list: D005819:Genetic Markers